Effective period / Period of releases: 1965 - 1993

This is an ambiguous name for one of two Vienna opera orchestras:

Orchester Der Wiener Staatsoper - in English, The Vienna State Opera Orchestra
Wiener Volksopernorchester - in English, The Vienna People's Opera Orchestra, or The Vienna National Opera Orchestra

The first is more likely, but it's worth checking other versions within a master release if the identity is not clear.

The name may also be chosen to deliberately make credits more obscure: one sign of this is the use of known bogus artists, like Alfred Scholz and Henry Adolph. In this case, use Orchester Der Wiener Staatsoper (2), Wiener Volksopernorchester (2) or Vienna Opera Orchestra.